1. Field of the Invention
This invention relates to novel optically active tolan derivatives which are useful as electrooptical display materials.
2. Description of Prior Art
In recent years, liquid crystal display cells of high multiplexing driving systems have been gradually increased in size, leading to an increasing demand as displays for computer terminals, TV sets and so forth. With this increase in demand, liquid crystal materials having high level multiplexibility have been more needed.
High level multiplexing driving systems are depending on change in the environmental temperature and the cross-talk phenomenon will easily occur. In order to prevent the formation of the cross-talk phenomenon due to changes in the environmental temperature, the following have been known; (1) a method in which a temperature compensation circuit is provide in the liquid crystal display equipment, and (2) a method in which the temperature dependency of threshold voltage of liquid crystal material is decreased by adding a chiral substance the molecular orientation of which is twisted right and a chiral substance the molecular orientation of which is twisted left, with respect to the liquid crystal material. The method (1), however, has a disadvantage in that the equipment becomes expensive. Also the method (2) has a disadvantage in that the amount of the substances added is limited because if the amount of the substances added is increased, the response time is decreased, although the substances are necessary to add in large amounts in order to sufficiently obtain the desired effect; therefore the desired effect cannot be obtained sufficiently.